How do I know what weight to use?

reader questionI get many questions sent to me here at Real Women’s Fitness and recently Shelly asked:

“How do I know which weight to use for each different exercise? Some muscles seem to need heavier weights and some need lighter weights.”

It is a really good question so I thought I would answer it here where everyone else can learn too.

How to choose the right weight

1. How much can you handle?
The first thing you need to do when trying to select the right weight is figure out what you can handle. For example, there is no point giving a 10 year old a 100 kilo barbell for his bench presses in the same way that there is no point in giving a professional bodybuilder a 20 kilo weight for his bench presses. Neither of them will get any benefit. So, first of all, establish how fit you are, how strong you are and how much you think you can handle. This is not an exact science but an approximate guess so that we have a place to start.

2. What muscle are you working?
Shelly is right when she says it seems that some muscles need more weight than others. They do. And this can make it a little bit confusing for beginners. A good example of this problem is to take a look at the legs and the biceps. The legs are much bigger than the biceps and can handle a lot more stress and weight.

The only way you will learn what muscles need what weight is through study and experience. It is a good idea to read up on the characteristics of each muscle so you have a vague idea in your head about what it can do with a weight. Then, through your own training, you should come to experience what weights bring the best results. As such it is a little bit of a trial and error.

3. What is the rep range?
This is the most important aspect of choosing a weight for your exercises. I have mentioned this many times before but some women still seem to miss the point of a rep range.

When you get a workout given to you by a trainer, website, etc. it will have a list of exercises with the amount of sets you should do and the amount of reps you should do. This last one is called the repetition range. For example, you might have something that looks like this:

Weighted Squats: 4 sets of 12 reps

This means that you are to do 4 sets of 12 repetitions of the squat. However, what many women don’t realize is that you are supposed to FAIL at 12. It does not mean that you just go out and do 12 reps of any weight and stop at 12 even if you can do more. That is pointless. What you need to do is pick a weight that forces you to fail at 12 reps. Fail is a bodybuilding term that means you can do no more. You need to stop.

So, essentially, it is the rep range that tells you what weight to use. Each well designed workout will tell you how many reps you should do for each exercise and if the trainer knows what they are talking about they would have taken into account whether the muscle needs more reps or less reps.

Once you start getting stronger you will find that the old weight doesn’t make you fail at the set number any more and that is when you need to add more weight. This is how weight lifting progress is made.

I hope that answers your question Shelly. Best of luck with the weight training!

Got more questions? Join our forum and ask us!

About Katie

Katie has transformed her body from a flabby 186lbs, to a fit & toned 124 pounds through healthy diet and exercise. Katie joined the Lean Curves team in 2007 and has posted hundreds of articles on fitness, fat loss and healthy eating.


  1. Shelly says:

    Thanks so much RT!

  2. Anna says:

    I had no idea thats what the rep. range meant! This is so exciting! Why hadn’t someone told me earlier?


  3. RT says:

    Shelly – no worries!

    Anna – glad to hear you learned something!


  4. Lisa Kelly says:

    Is this the same method used for weight loss? Reps

  5. cara1011 says:

    But if you fail after 12 reps how can you do 4 sets…I don’t get it.

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